阅读说明：本技术 一种聚磷酸哌嗪复合阻燃剂及其制备方法 (Polyphosphoric acid piperazine composite flame retardant and preparation method thereof ) 是由 叶丹阳 李俊彬 田志雄 姚小龙 何伟 李凤宇 谌能办 金凤 孟喜 于 2020-06-11 设计创作，主要内容包括：本发明公开了一种聚磷酸哌嗪复合阻燃剂,按质量百分比包括以下组分：聚磷酸哌嗪87.1％～99.4％,硅烷偶联剂0.5％～7.1％,抗氧剂0.1％～5.8％；所述硅烷偶联剂包覆于聚磷酸哌嗪外层；本发明还公开了该聚磷酸哌嗪复合阻燃剂的制备方法,将磷酸水溶液和哌嗪加入反应装置中,搅拌；通入保护性气体,加入抗氧剂,升高温度进行脱水缩合反应,制得聚磷酸哌嗪；降温,加入硅烷偶联剂混合包覆,出料；该方法产率高、成本低、易操作,采用该方法制得的聚磷酸哌嗪复合阻燃剂白度高、耐水性好、阻燃效率高、材料相容性好。(The invention discloses a polyphosphoric acid piperazine composite flame retardant which comprises the following components in percentage by mass: 87.1 to 99.4 percent of polyphosphoric acid piperazine, 0.5 to 7.1 percent of silane coupling agent and 0.1 to 5.8 percent of antioxidant; the silane coupling agent is coated on the outer layer of polyphosphoric acid piperazine; the invention also discloses a preparation method of the polyphosphoric acid piperazine compound flame retardant, wherein phosphoric acid aqueous solution and piperazine are added into a reaction device and stirred; introducing protective gas, adding an antioxidant, raising the temperature, and performing dehydration condensation reaction to prepare polyphosphoric acid piperazine; cooling, adding a silane coupling agent, mixing and coating, and discharging; the method has the advantages of high yield, low cost and easy operation, and the polyphosphoric acid piperazine composite flame retardant prepared by the method has high whiteness, good water resistance, high flame retardant efficiency and good material compatibility.)

1. The piperazine polyphosphate composite flame retardant is characterized by comprising the following components in percentage by mass: 87.1 to 99.4 percent of polyphosphoric acid piperazine, 0.5 to 7.1 percent of silane coupling agent and 0.1 to 5.8 percent of antioxidant; the silane coupling agent is coated on the outer layer of polyphosphoric acid piperazine.

2. The piperazine polyphosphate composite flame retardant according to claim 1, wherein the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant CA, antioxidant 164, antioxidant DNP, antioxidant DLTP and antioxidant TNP.

3. The piperazine polyphosphate composite flame retardant according to claim 1, wherein the silane coupling agent is one of vinyl silane, amino silane, epoxy silane and methacryloxy silane.

4. The preparation method of the piperazine polyphosphate composite flame retardant is characterized by comprising the following steps:

s1: adding phosphoric acid aqueous solution and piperazine into a reaction device, and stirring;

s2: introducing protective gas, adding an antioxidant, raising the temperature, and performing dehydration condensation reaction to prepare polyphosphoric acid piperazine;

s3: and cooling, adding a silane coupling agent, mixing and coating, and discharging to obtain the polyphosphoric acid piperazine composite flame retardant.

5. The preparation method of the piperazine polyphosphate composite flame retardant according to claim 4, wherein the molar ratio of phosphoric acid to piperazine is 1: 1-4: 1; the mass ratio of the antioxidant to the phosphoric acid is 1: 1000-8: 100; the mass ratio of the silane coupling agent to the phosphoric acid is 1: 100-1: 5.

6. The preparation method of the piperazine polyphosphate composite flame retardant according to claim 5, wherein the molar ratio of phosphoric acid to piperazine is 1.5: 1-3: 1; the mass ratio of the antioxidant to the phosphoric acid is 1: 100-6: 100; the mass ratio of the silane coupling agent to the phosphoric acid is 3: 100-3: 50.

7. The preparation method of the piperazine polyphosphate composite flame retardant according to claim 4, wherein the phosphoric acid content of the phosphoric acid aqueous solution is not less than 50%.

8. The preparation method of the piperazine polyphosphate composite flame retardant according to claim 4, wherein the reaction temperature in the step S1 is 60-100 ℃, and the stirring time is 1-6 hours.

9. The preparation method of the piperazine polyphosphate composite flame retardant according to claim 4, wherein the protective gas in the step S2 is inert gas or nitrogen, the temperature is raised to 200-300 ℃, and the heat is preserved for 0.5-3 h to prepare the piperazine polyphosphate.

10. The preparation method of the piperazine polyphosphate composite flame retardant according to claim 4, wherein the temperature is reduced to 60-90 ℃ in the step S3.

Technical Field

The invention relates to the technical field of flame retardants, in particular to a polyphosphoric acid piperazine composite flame retardant and a preparation method thereof.

Background

With the rapid development of Chinese economy, the consumption of the flame retardant is greatly increased, the attention degree of the Chinese government on the health and safety conditions of fire fighting and consumers is improved, the development of the flame retardant industry is facilitated, the Chinese flame retardant demand keeps 8 percent of the increase rate every year, and the market value reaches 22.45 billion dollars. Because domestic environmental protection standards and regulations are not perfect, domestic flame retardants are still mainly halogen, but with the enhancement of domestic environmental protection consciousness, the development potential of halogen-free flame retardants is huge. The halogen-free flame retardant may be phosphorus flame retardant, nitrogen flame retardant, boron flame retardant, silicon flame retardant, metal hydroxide flame retardant, intumescent flame retardant, etc. depending on the main elements contained in the flame retardant.

The phosphorus-nitrogen synergistic flame retardant is also called an Intumescent Flame Retardant (IFR), contains C, N, P as the main element, has the advantages of low smoke, low toxicity, high efficiency, environmental protection, small addition amount, good flame retardance and the like, and is widely applied in the fields of paint, rubber, wood and particularly plastics; the carbon residue layer is covered with glassy thin-layer polymetaphosphoric acid to inhibit further oxidation of the carbon layer, and the nitrogen-containing component is decomposed into ammonia gas, nitrogen gas and other nonflammable gases to dilute the flammable gases, slow down the spread of combustion and promote the formation of an expanded carbon layer.

Intumescent flame retardants can be divided into mixed intumescent flame retardants and single component intumescent flame retardants. The IFR used in the current market mainly adopts a multi-component formula taking ammonium polyphosphate (APP) with large molecular weight as an acid source, and the mixed IFR has the characteristics of wide sources of three-source components, simple composite processing technology, low cost and the like, but the proportion among the acid source, the carbon source and the gas source is extremely complex, the proportion relation among the three is difficult to control, and the systems are easy to have the phenomenon of uneven dispersion of a flame retardant in a polymer due to uneven mixing, so that the synergistic effect is not ideal, and the flame retardant efficiency is reduced or the flame retardant result is unstable, and the defects of easy moisture absorption, precipitation and the like are caused; the single-component intumescent flame retardant contains a part which can play the roles of an acid source, a carbon source and a gas source in the same molecule, has excellent moisture absorption resistance, thermal stability and compatibility, and can well overcome the problems of the multi-component flame retardant. The polyphosphoric piperazine (PPAP) is a P-N type monomolecular intumescent flame retardant obtained by reacting piperazine with other phosphorus-containing bifunctional compounds based on a phosphorus/nitrogen synergistic flame retardant principle, and is a hotspot and a key point for developing novel intumescent flame retardants at present; structurally, the polyphosphate piperazine belongs to phosphate polymers like APP, but is different from APP in that the polyphosphate piperazine is not only a good acid source but also an excellent char-forming agent and also has the function of a foaming agent; in addition, the piperazine ring structure is similar to a benzene ring, so that the piperazine ring structure has outstanding thermal stability, the piperazine chain segment is also possible to improve the interaction between the inorganic flame retardant and a polymer matrix, and the flame retardant prospect is good.

The existing preparation method of the piperazine polyphosphate flame retardant roughly comprises the following steps: 1) the double decomposition method is characterized in that sodium pyrophosphate and piperazine are used for generating a water-insoluble piperazine polyphosphate precipitate product in a hydrochloric acid solution, and the method has the problems that by-product sodium chloride or piperazine sodium pyrophosphate is generated, the yield of a target product is reduced, and the flame retardant property of the product is influenced; 2) the phosphorus pentoxide method, utilize phosphorus pentoxide, piperazine in the presence of oxalic acid through the water that oxalic acid decomposes and produces make phosphorus pentoxide produce pyrophosphoric acid, and then form salt with piperazine, this method has long reaction implementation step, and in the actual application because of the volatilization of piperazine, phosphorus pentoxide depolymerization degree is difficult to control, the temperature is slightly high causes piperazine carbonization, cause the lower problem of actual efficiency; 3) ammonium dihydrogen phosphate method, this method uses ammonium dihydrogen phosphate to replace phosphoric acid solution as the acid source to react with piperazine, ammonium dihydrogen phosphate and piperazine remove ammonia and produce the midbody first, through dehydrating the condensation reaction, thus get PPAP powder, this method has overcome the corrosion to apparatus while using liquid phosphoric acid usually with solid phosphorus source, the ammonia released in the reaction can be regarded as the protective atmosphere of the reaction system, but there is the question of exhaust emission too; 4) the method comprises the steps of firstly, reacting phosphoric acid and piperazine in solvents such as water and acetic acid to prepare intermediate piperazine diphosphate, precipitating crystals of the intermediate piperazine diphosphate, and then carrying out high-temperature dehydration condensation on the piperazine diphosphate to prepare polyphosphoric acid piperazine.

Piperazine polyphosphate has many advantages, but the current industrial production process has certain defects, and the compatibility of piperazine polyphosphate and a high polymer material system is poor, when piperazine polyphosphate is used, the piperazine polyphosphate is a powder material and is simply and physically mixed with the high polymer material, the uniformity is poor, the actual effect of a flame retardant in a formula is not fully exerted, and a migration phenomenon also exists in the use process of the material, and meanwhile, a large number of fine cracks exist in piperazine polyphosphate crystals in the synthesis process, so that the piperazine polyphosphate has the problems of moisture absorption, poor water resistance and influence on the appearance size stability of a product.

Disclosure of Invention

In view of the above problems, a first object of the present invention is to provide a piperazine polyphosphate composite flame retardant; the silane coupling agent is coated on the outer layers of the piperazine polyphosphate and the antioxidant, so that the prepared piperazine polyphosphate composite flame retardant has high whiteness, good water resistance, good flame retardant property and good material compatibility.

The second purpose of the invention is to provide the preparation method of the piperazine polyphosphate composite flame retardant, the piperazine polyphosphate is directly synthesized by adopting a one-step method, the preparation process of the piperazine polyphosphate is simplified, the yield is improved, the antioxidant is added in the step of high-temperature dehydration condensation, the problems of yellowing and low whiteness of the piperazine polyphosphate caused by high temperature are solved, and the whiteness of the product piperazine polyphosphate composite flame retardant is improved; in the method, piperazine is added to react with phosphoric acid aqueous solution, then a silane coupling agent is added to carry out coating, and the final polyphosphoric acid piperazine composite flame retardant is directly prepared from the raw material piperazine through one-time process operation; compared with the method that the raw material piperazine polyphosphate is added and the silane coupling agent is added for coating, the method directly prepares the piperazine polyphosphate composite flame retardant through the raw material piperazine by one-step process, thereby greatly reducing the production cost; moreover, the method is suitable for batch production, high in yield and easy to operate.

The first technical scheme adopted by the invention is as follows: the polyphosphoric acid piperazine composite flame retardant comprises the following components in percentage by mass: 87.1 to 99.4 percent of polyphosphoric acid piperazine, 0.5 to 7.1 percent of silane coupling agent and 0.1 to 5.8 percent of antioxidant; the silane coupling agent is coated on the outer layer of polyphosphoric acid piperazine.

Preferably, the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant CA, antioxidant 164, antioxidant DNP, antioxidant DLTP and antioxidant TNP.

Preferably, the silane coupling agent is one of vinyl silane, amino silane, epoxy silane and methacryloxy silane.

The second technical scheme adopted by the invention is as follows: the preparation method of the piperazine polyphosphate composite flame retardant comprises the following steps:

s1: adding phosphoric acid aqueous solution and piperazine into a reaction device, and stirring;

s2: introducing protective gas, adding an antioxidant, raising the temperature, and performing dehydration condensation reaction to prepare polyphosphoric acid piperazine;

s3: and cooling, adding a silane coupling agent, mixing and coating, and discharging to obtain the polyphosphoric acid piperazine composite flame retardant.

Preferably, the molar ratio of the phosphoric acid to the piperazine is 1: 1-4: 1; the mass ratio of the antioxidant to the phosphoric acid is 1: 1000-8: 100; the mass ratio of the silane coupling agent to the phosphoric acid is 1: 100-1: 5.

Preferably, the molar ratio of the phosphoric acid to the piperazine is 1.5: 1-3: 1; the mass ratio of the antioxidant to the phosphoric acid is 1: 100-6: 100; the mass ratio of the silane coupling agent to the phosphoric acid is 3: 100-3: 50.

Preferably, the phosphoric acid content of the phosphoric acid aqueous solution is more than or equal to 50 percent.

Preferably, the reaction temperature in the step S1 is 60-100 ℃, and the stirring time is 1-6 h.

Preferably, the protective gas in the step S2 is inert gas or nitrogen, the temperature is raised to 200-300 ℃, and the heat is preserved for 0.5-3 hours to prepare polyphosphoric acid piperazine.

Preferably, the temperature in step S3 is reduced to 60 ℃ to 90 ℃.

The beneficial effects of the above technical scheme are that:

(1) the piperazine polyphosphate composite flame retardant prepared by the invention can be directly used without other treatment, and is flame retardant powder which can be directly used for modified plastics.

(2) Compared with a piperazine diphosphate condensation method, the method provided by the invention has the advantages that the polyphosphoric acid piperazine is directly synthesized by a one-step method, so that the precipitation of an intermediate piperazine diphosphate is avoided, and the yield is improved; and the phosphoric acid aqueous solution is directly used for reaction, the reaction process is green and environment-friendly, and the production cost is low.

(3) According to the invention, the antioxidant is added in the high-temperature condensation dehydration reaction stage, so that the sensitivity of the intermediate product to oxygen is reduced, the problems of yellowing and low whiteness of the prepared piperazine polyphosphate under a high-temperature condition are solved, the whiteness and the competitiveness of the product piperazine polyphosphate composite flame retardant are improved, and the control difficulty of key quality indexes in the production process of the piperazine polyphosphate composite flame retardant is reduced.

(4) According to the invention, the polyphosphoric acid piperazine is obtained by directly synthesizing raw material piperazine and phosphoric acid aqueous solution, and then the polyphosphoric acid piperazine is coated by taking a silane coupling agent as a coating material, so that the water resistance of the polyphosphoric acid piperazine is improved, the flame retardant efficiency of the polyphosphoric acid piperazine is improved, and the use cost of the flame retardant is reduced.

(5) The polyphosphoric acid piperazine compound flame retardant is directly prepared from raw material piperazine through a one-step process, and the method is suitable for batch production, high in yield and easy to operate.

(6) According to the preparation method of the piperazine polyphosphate composite flame retardant disclosed by the invention, the piperazine polyphosphate composite flame retardant with high whiteness, good water resistance and good material compatibility can be directly obtained through a one-step process by using the raw material piperazine without changing the conventional synthesis production condition, so that the production cost is reduced, and the comprehensive competitiveness of the piperazine polyphosphate composite flame retardant as a composite flame retardant is enhanced.

Drawings

FIG. 1 is a flow chart of a preparation process of a piperazine polyphosphate composite flame retardant;

FIG. 2 is a reaction scheme of the piperazine polyphosphate synthesis route of the present invention;

FIG. 3 is a particle size distribution diagram of a piperazine polyphosphate composite flame retardant prepared in example 1 of the present invention;

FIG. 4 is a particle size distribution diagram of a piperazine polyphosphate composite flame retardant prepared in example 2 of the present invention;

FIG. 5 is a particle size distribution diagram of a piperazine polyphosphate composite flame retardant prepared in example 3 of the present invention.

Detailed Description

The present invention is further illustrated by the following specific examples, it should be noted that, for those skilled in the art, variations and modifications can be made without departing from the principle of the present invention, and these should also be construed as falling within the scope of the present invention.

The invention discloses a polyphosphoric acid piperazine composite flame retardant which comprises the following components in percentage by mass: 87.1 to 99.4 percent of polyphosphoric acid piperazine, 0.5 to 7.1 percent of silane coupling agent and 0.1 to 5.8 percent of antioxidant; the silane coupling agent is coated on the outer layer of the polyphosphoric acid piperazine.

The antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant CA, antioxidant 164, antioxidant DNP, antioxidant DLTP and antioxidant TNP. The silane coupling agent is one of vinyl silane, amino silane, epoxy silane and methacryloxy silane, and the specific trade mark includes but is not limited to KH-540, KH-550, KH-560, KH-570, KH-590, A-151, A-171, A-172, Si-563 and YDH-201.

As shown in fig. 1, the piperazine polyphosphate composite flame retardant is prepared by the following steps:

s1: adding phosphoric acid aqueous solution and piperazine into a reaction device, stirring and reacting for 1-6 h at the temperature of 60-100 ℃, wherein the phosphoric acid content of the phosphoric acid aqueous solution is more than or equal to 50%; the reaction apparatus is an apparatus capable of heating and dehydrating, such as an extruder, a kneader, a mixer, etc.

S2: introducing inert gas or nitrogen, adding an antioxidant, raising the temperature to 200-300 ℃ for dehydration condensation reaction, and keeping the temperature for 0.5-3 h to prepare polyphosphoric acid piperazine; the reaction formula of the piperazine polyphosphate synthetic route is shown in figure 2.

S3: cooling to 60-90 ℃, adding a silane coupling agent, mixing and coating uniformly, cooling to room temperature, and discharging; and continuously carrying out three steps of reactions to obtain the polyphosphoric acid piperazine composite flame retardant.

The molar ratio of the phosphoric acid to the piperazine is 1: 1-4: 1, preferably 1.5: 1-3: 1; the mass ratio of the antioxidant to the phosphoric acid is 1: 1000-8: 100, preferably 1: 100-6: 100; the mass ratio of the silane coupling agent to the phosphoric acid is 1: 100-1: 5, preferably 3: 100-3: 50.

The prepared piperazine polyphosphate composite flame retardant is characterized by comprising the following components in parts by weight:

1) particle size

And detecting the particle size of the prepared piperazine polyphosphate composite flame retardant by using a laser particle sizer.

2) Whiteness degree

And (3) performing whiteness detection on the prepared piperazine polyphosphate composite flame retardant by adopting a whiteness measuring instrument.

3) Water resistance

The water resistance detection is carried out according to the solubility of the product in water, specifically, products to be detected with different masses are added into 100mL of water, and the greater the mass of each product to be detected dissolved in 100mL of water is, namely the greater the solubility is, the poorer the water resistance is.